Over-voltage protection circuits are often implemented in electronic devices to protect the internal components of these devices from over-voltage conditions associated with the device inputs. For example, an over-voltage condition can occur when an external accessory or component is connected or disconnected from an input of a device while the external accessory or component is active. Such an over-voltage condition may be characterized by a large positive or negative voltage spike that could damage the internal components or circuitry of the device in the absence of an appropriately implemented over-voltage protection circuit.
Many existing over-voltage protection circuits are implemented using active clamp circuits that direct the voltage associated with a device input to ground when an over-voltage condition occurs and/or is detected. However, a typical active clamp circuit requires an active power source to be operational and, thus, may not provide adequate over-voltage protection when the device being protected is inactive.